High performance imaging spectrometers are in demand for use for a wide range of applications, for example, from satellite imagery to food safety. In a typical form, an imaging spectrometer images an entrance slit onto a 2D (two-dimensional) detector array where the length of the slit extends along a first of the dimensions of the 2D detector array and the dispersion created by a diffraction grating relatively displaces images of the slit in a second orthogonal dimension of the 2D detector array. Displacements of the slit images in the second dimension register the spectral content of light collected through the entrance slit.
A hyperspectral image of a scene is captured by incorporating fore-optics for imaging a slice of a scene onto the slit and translating the spectrometer in a so-called “pushbroom” manner to capture contiguous images of the scene's spatial radiance distribution. Each pixel of the scene is associated with a substantially contiguous spectrum spread over the second orthogonal dimension of the 2D detector array.
More stringent performance objectives continue to be set for imaging spectrometers such as increasing spectral range and spectral resolution, decreasing package size, and enlarging the field of view. Efforts to meet the more stringent performance objectives have led to developments utilizing technologies such as volume phase holography, digital micromirror devices (DMDs), and multispectral photodiodes. However, the improvements made possible by these new technologies have been limited or involved tradeoffs in which the performance gains achieved for one objective are offset by performance losses encountered for other objectives.